Physics, asked by rahulgond031, 1 year ago

m confused about "Energy can nither be created nor be destroyed".....let that a car is moving means it have K.E now it stops then it produce heat enery in it's tyers...after some times tyer get cooled.....it's means it lost energy????...than how it's true that "energy can nither be created nor be destroyed"????...
Second question- As we know that K.E +P.E= constant.....we throw a ball vertically upward then it's K.E changes in P.E ok...and when the ball comes down then it's​ P.E changes in K.E..... all right now a plane is moving in air then it has K.E as well as P.E...and we know that K.E + P.E is coantant then how it is possible in class of plane???

Answers

Answered by Anonymous
3
First question:

Yep, thermodynamics says that energy can never be created nor destroyed, but CAN BE CHANGED TO SOME OTHER FORM , OR DISSIPATE.

Now, okay the tyres get heated up , they do cool down after sometime, but that doesn't mean that a superhuman force ou of nowhere just took away all of its heat energy - the energy of the tyre flows to the air and land molecules in its vicinity. Air near it gets heated, acquires its energy, but you may not feel the air hot as you know all the heat is not lost to just the same unit volume of air, that is, intensity is low



Question 2: Total energy of an ISOLATED body is conserved, not just mechanical. Total energy in a closed system is same, bear in mind.

Now to your question, yep, the neglecting the dissipation you can consider the mechanical energy to be constant, but CONSTANT MEANS SHOWING CONSISTENCY, IT DOESN'T IMPLY HAVING THE SAME UNIVERSAL VALUE, since NEGLECTING DISSIPATION mechanical energy, as you wish, is constant, that means the sum of kinetic and potential is same throughout, as the plane is up high in the sky it's gonna have the same, consistent sum of potential and kinetic energy, UNLESS YOU INVEST YOUR ENERGY THEREIN, IN THAT SYSTEM.








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